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[en] METROLOGICAL CONFIDENCE AND VALIDATION OF SPECTRORADIOMETRIC PROCEDURES FOR THE MEASUREMENT OF LIGHT SOURCES / [pt] CONFIABILIDADE METROLÓGICA E VALIDAÇÃO DE PROCEDIMENTOS ESPECTRORADIOMÉTRICOS PARA MEDIÇÃO DE FONTES LUMINOSASDANIELLE FERREIRA DE OLIVEIRA 22 November 2006 (has links)
[pt] A avaliação e a caracterização da cor constituem fatores
críticos do
processo de controle de qualidade de produtos, que também
devem atender
exigências dos clientes e consumidores finais. A cor de um
objeto depende
fortemente das características da iluminação. Nesse
contexto, a presente
pesquisa analisou e comparou os diferentes métodos
especificados em normas
internacionais, que qualificam o desempenho dos
simuladores de luz do dia
utilizados em avaliações visuais (cabines de luz) e
instrumentais
(espectrofotômetros). Para alcançar tais objetivos, foram
verificadas as
condições de medição estabelecidas pela CIE (intervalo de
medição e largura de
banda espectral) e elaborados e validados procedimentos de
medição de
diferentes fontes luminosas. Com base nestes
procedimentos, foram realizadas
medições de simuladores de luz do dia para adquirir as
suas distribuições
espectrais de potência, as quais foram utilizadas para
avaliá-los e para comparar
os métodos especificados em normas. Como principais
resultados da pesquisa
destacam-se: (i) a constatação de que, de fato, as
recomendações da CIE para
medição de fontes luminosas devem ser incorporadas ao
processo de medição;
(ii) o aumento da confiabilidade metrológica através da
validação dos
procedimentos espectroradiométricos com base em análises
de repetitividade
das medições; e (iii) a comparação realizada entre os
diferentes métodos de
avaliação de simuladores de luz do dia, o que permitiu
documentar para os
casos estudados a presença ou a falta de correlação entre
os mesmos. O
trabalho contribuiu também ao introduzir uma sistemática
normalizada de rotinas
para se expressar a incerteza associada à medição
espectroradiométrica. / [en] The evaluation and the characterization of the colour
constitute critical
factors of the process of quality control of products,
that also must take care of
requirements imposed by customers and final consumers. The
colour of an object
depends greatly on the characteristics of the
illumination. In this context, this
research is aimed at discussing the different
international standards that
characterize the performance of the daylight simulators
used in instrumental
(spectrophotometers) and visual (light booths) evaluations
and also at analysing
the differences between the various methods specified in
these standards. To
reach these objectives the measurement conditions
established by the CIE
(interval and spectral band-width) were verified and
elaborated and validated
procedures for the measurement of different luminous
sources. Based on these
procedures, measurements of daylight simulators were
carried out to acquire
their spectral power distributions. The measurement
results were then used to
analyze the evaluations methods specified in standards.
The following main
results have been accomplished: (i) the CIE
recommendations for the
measurement of luminous sources must, in fact, be
incorporated into the
measurement process; (ii) the increase in the metrological
reliability through the
validation of the spectroradiometric procedures based on
the analyses of the
repeatability of the measurements; and (iii) the
comparison established among
the different evaluation methods of daylight simulators,
leading to the distinction
between the presence or the lack of correlation present in
the different methods
investigated. The work also contributed by the
introduction of standard routines to
express the uncertainty associated with spectroradiometric
measurements.
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Astrofísica Estelar para o Ensino Médio: Uma abordagem empírica baseada na observação visual das estrelas variáveis / Stellar Astrophysics for the high school level: an empirical approach based on the visual observation of variable stars.Napoleão, Tasso Augusto Jatobá 17 April 2018 (has links)
Este trabalho tem como objetivo o ensino dos fundamentos da Astrofísica Estelar moderna a alunos do Ensino Médio através de uma abordagem empírica que usa como ferramentas principais da metodologia a observação, o registro, a análise e a interpretação das mudanças de brilho das estrelas variáveis ao longo do tempo. Mediante técnicas simples (fotometria visual) para a estimativa dos valores dos brilhos aparentes (magnitudes) dessas estrelas no decorrer de vários meses, o aluno coleta seus próprios dados observacionais. Em seguida, esses dados serão colocados em gráficos (curvas de luz), cuja análise permitirá a medida de seus períodos e amplitudes de variação, bem como a determinação de uma série de parâmetros que caracterizam as propriedades físicas das estrelas. O estudo é conduzido de uma forma que permite apresentar aos alunos vários dos grandes temas da Astrofísica contemporânea sem que eles percam o vínculo sensorial com a observação direta dos fenômenos celestes, seja com auxílio de instrumental modesto (binóculos ou pequenos telescópios), seja até mesmo a olho nu. O produto final de nosso trabalho é um Guia de Estudos intitulado Astrofísica Estelar para o Ensino Médio, em doze capítulos e mais de trezentas páginas, que está incluído em sua íntegra nesta monografia. O Guia foi desenvolvido tendo como alvos principais os alunos e professores do Ensino Médio formal. Não obstante, ele pode ser também utilizado por qualquer pessoa que tenha interesse no assunto e que possua os conceitos necessários de Matemática e Física do Ensino Médio; ou ainda em cursos do ensino não-formal que sejam ministrados, por exemplo, por planetários, museus de ciência e astrônomos amadores (situação essa testada com ótimos resultados pelo autor). Por fim, vale mencionar que, neste tipo de aprendizado (conhecido como research-based education, que poderíamos traduzir livremente como aprendizado vinculado à pesquisa), utilizamos intensivamente diversos recursos tecnológicos disponibilizados gratuitamente na internet pelas grandes entidades internacionais que se dedicam à pesquisa e ao estudo das estrelas variáveis tais como softwares específicos, bancos de dados, simulações e cartas para a estimativa das magnitudes. O uso dessa metodologia vinculada à pesquisa, em nossa experiência, se constitui em um fator valioso para desenvolver nos alunos a criatividade, o raciocínio crítico, a familiarização com o método científico e as habilidades para a pesquisa. / This work aims at teaching the fundamental aspects of Stellar Astrophysics to high school students through an empirical approach which uses variable stars observations, data collection, and the analysis and interpretation of brightness changes as key methodological tools. By using some simple techniques (visual photometry) to estimate the values of apparent brightness (magnitudes) of these stars over several months, the student collects his/her own observational data. Subsequently, that data will be plotted in graphs (light curves), whose analysis will in turn allow the determination of its periods and amplitudes of variation, as well as of a series of physical parameters that characterize the physical properties of the stars. The whole study is conducted in a way that shows students several of the major themes of contemporary Astrophysics without losing their sensory link with the direct observation of celestial phenomena - whether with the aid of modest instruments (binoculars or small telescopes) or even naked eye. The final product of our work is a Study Guide called \"Stellar Astrophysics for High School\" in twelve chapters and more than three hundred pages, which is included in their entirety in this monograph. The Guide was developed with the main targets being students and teachers of the formal high school level. Nevertheless, it can also be used by anyone who has an interest in the subject and who possesses the required concepts of high school Mathematics and Physics; or even in non-formal teaching courses that are taught, for example, by planetariums, science museums and amateur astronomers (a situation that has been tested with great results by the author). Last but not least, it is worth mentioning that in this type of learning (known as \"research-based education\") we intensively use various technological resources freely available on the internet from the great international entities that are dedicated to the research and study of variable stars such as specific softwares, databases, simulations and charts for estimating magnitudes. The use of research-based education, in our experience, is a valuable tool to foster and develop students creativity, critical thinking, and the familiarization with the scientific method and research skills.
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Astrofísica Estelar para o Ensino Médio: Uma abordagem empírica baseada na observação visual das estrelas variáveis / Stellar Astrophysics for the high school level: an empirical approach based on the visual observation of variable stars.Tasso Augusto Jatobá Napoleão 17 April 2018 (has links)
Este trabalho tem como objetivo o ensino dos fundamentos da Astrofísica Estelar moderna a alunos do Ensino Médio através de uma abordagem empírica que usa como ferramentas principais da metodologia a observação, o registro, a análise e a interpretação das mudanças de brilho das estrelas variáveis ao longo do tempo. Mediante técnicas simples (fotometria visual) para a estimativa dos valores dos brilhos aparentes (magnitudes) dessas estrelas no decorrer de vários meses, o aluno coleta seus próprios dados observacionais. Em seguida, esses dados serão colocados em gráficos (curvas de luz), cuja análise permitirá a medida de seus períodos e amplitudes de variação, bem como a determinação de uma série de parâmetros que caracterizam as propriedades físicas das estrelas. O estudo é conduzido de uma forma que permite apresentar aos alunos vários dos grandes temas da Astrofísica contemporânea sem que eles percam o vínculo sensorial com a observação direta dos fenômenos celestes, seja com auxílio de instrumental modesto (binóculos ou pequenos telescópios), seja até mesmo a olho nu. O produto final de nosso trabalho é um Guia de Estudos intitulado Astrofísica Estelar para o Ensino Médio, em doze capítulos e mais de trezentas páginas, que está incluído em sua íntegra nesta monografia. O Guia foi desenvolvido tendo como alvos principais os alunos e professores do Ensino Médio formal. Não obstante, ele pode ser também utilizado por qualquer pessoa que tenha interesse no assunto e que possua os conceitos necessários de Matemática e Física do Ensino Médio; ou ainda em cursos do ensino não-formal que sejam ministrados, por exemplo, por planetários, museus de ciência e astrônomos amadores (situação essa testada com ótimos resultados pelo autor). Por fim, vale mencionar que, neste tipo de aprendizado (conhecido como research-based education, que poderíamos traduzir livremente como aprendizado vinculado à pesquisa), utilizamos intensivamente diversos recursos tecnológicos disponibilizados gratuitamente na internet pelas grandes entidades internacionais que se dedicam à pesquisa e ao estudo das estrelas variáveis tais como softwares específicos, bancos de dados, simulações e cartas para a estimativa das magnitudes. O uso dessa metodologia vinculada à pesquisa, em nossa experiência, se constitui em um fator valioso para desenvolver nos alunos a criatividade, o raciocínio crítico, a familiarização com o método científico e as habilidades para a pesquisa. / This work aims at teaching the fundamental aspects of Stellar Astrophysics to high school students through an empirical approach which uses variable stars observations, data collection, and the analysis and interpretation of brightness changes as key methodological tools. By using some simple techniques (visual photometry) to estimate the values of apparent brightness (magnitudes) of these stars over several months, the student collects his/her own observational data. Subsequently, that data will be plotted in graphs (light curves), whose analysis will in turn allow the determination of its periods and amplitudes of variation, as well as of a series of physical parameters that characterize the physical properties of the stars. The whole study is conducted in a way that shows students several of the major themes of contemporary Astrophysics without losing their sensory link with the direct observation of celestial phenomena - whether with the aid of modest instruments (binoculars or small telescopes) or even naked eye. The final product of our work is a Study Guide called \"Stellar Astrophysics for High School\" in twelve chapters and more than three hundred pages, which is included in their entirety in this monograph. The Guide was developed with the main targets being students and teachers of the formal high school level. Nevertheless, it can also be used by anyone who has an interest in the subject and who possesses the required concepts of high school Mathematics and Physics; or even in non-formal teaching courses that are taught, for example, by planetariums, science museums and amateur astronomers (a situation that has been tested with great results by the author). Last but not least, it is worth mentioning that in this type of learning (known as \"research-based education\") we intensively use various technological resources freely available on the internet from the great international entities that are dedicated to the research and study of variable stars such as specific softwares, databases, simulations and charts for estimating magnitudes. The use of research-based education, in our experience, is a valuable tool to foster and develop students creativity, critical thinking, and the familiarization with the scientific method and research skills.
|
254 |
Spectrophotometric properties of the nucleus of the comet 67P/Churyumov-Gerasimenko observed by the ROSETTA spacecraft / Propriétés spectrophotométriques du noyau de la comète 67P/Churyumov-Gerasimenko observée par la sonde ROSETTAJasinghege Don, Prasanna Deshapriya 12 September 2018 (has links)
Cette thèse s'inscrit dans le cadre de la mission spatiale Rosetta et porte sur les propriétés spectrophotométriques de la comète 67P/Churyumov-Gerasimenko à l’aide de l’instrument OSIRIS. Cet instrument est composé de deux caméras pour les observations du noyau et de la coma de la comète. Elles permettent d’acquérir des images avec des filtres qui opèrent dans la gamme du proche UV au proche IR. Dans un premier temps, j'ai analysé les courbes spectrophotométriques des taches claires qui sont apparues sur le noyau de la comète. Une étude comparative de celles-ci grâce aux données du spectro-imageur VIRTIS a ainsi permis de constater que les taches claires sont liées à la glace de H2O. Dans un second temps, j’ai entrepris une étude spectrophotométrique de la région Khonsu, qui a mis en évidence les variations saisonnières de la pente spectrale de différents terrains. Par la suite, j’ai élargi mon analyse des taches à tout le noyau de la comète. J’ai détecté plus de 50 taches claires dues à la présence de glace de H2O et j’ai produit une carte pour repérer leurs emplacements sur le noyau, afin d’étudier plus en détail leur répartition et leur évolution au cours de temps. Ceci m’a permis d’identifier quatre types de taches regroupés en fonction de leur morphologie et de constater qu'elles sont dues à différentes sources d'activité cométaire. / This thesis is based on the spectrophotometric properties of the comet 67P/Churyumov-Gerasimenko, using the OSIRIS instrument of Rosetta space mission. Composed of two scientific cameras to observe the nucleus and the coma of the comet, OSIRIS images are acquired with multiple filters, that span the near-UV to near-IR wavelength range. They were used to study the spectrophotometric curves of the exposed bright features that appeared on the surface of the cometary nucleus, leading to a comparative study, that was carried out in collaboration with the VIRTIS spectro-imager aboard Rosetta, that demonstrated, that these exposures are related to H2O ice, using its absorption band located at 2 microns. The thesis further details a spectrophotometric study of the Khonsu region in the southern latitudes of the comet, where the seasonal variation of the spectral slope of different types of terrains is explored. Finally, the results of an extended survey of exposed bright features are presented. More than 50 individual features are presented under four morphologies along with an albedo calculation, suggesting that different activity sources are responsible for their appearance on the nucleus.
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Gravitational Microlensing: GPU-based Simulation Algorithms and the Information Content of Light Curves / Der Mikrogravitationslinseneffekt: GPU-basierte Simulationsalgorithmen und der Informationsgehalt von LichtkurvenHundertmark, Markus Peter Gerhard 20 June 2011 (has links)
No description available.
|
256 |
Formation and evolution of star clusters in interacting galaxies / Entstehung und Entwicklung von Sternhaufen in wechselwirkenden GalaxienAnders, Peter 20 February 2006 (has links)
No description available.
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257 |
A search for pulsating B-type variable stars in the southern open clusters NGC 6204 and Hogg 22 / Jacobus Johannes (Jaco) MentzMentz, Jacobus Johannes January 2013 (has links)
The theory of stellar evolution and stellar structure relies on the observation of stars
in di erent phases of their evolutionary cycle. The relation between observations and
theory can be strengthened by obtaining observational data of a large sample of stars in a particular evolutionary phase. The search for Cephei stars, as conducted in this study,
can contribute to the sample of known Cephei stars, where these interesting stars are
massive non-supergiant early B-type stars, displaying pulsating behaviour which is not
well understood.
Stars tend to form in clusters where it can therefore be expected that young massive
stars can be found in open clusters. For this reason two young southern open clusters
were observed in order to search for B-type pulsating stars. The region of NGC 6204
and Hogg 22 was observed over a period of thirteen nights in Johnson B, V and I bands.
NGC 6204 is believed to be the oldest cluster of the two at a distance of 0.8 kpc while the
much younger Hogg 22 is more distant at 2.8 kpc. These two open clusters are located
6 arcminutes apart which made it possible to observe them simultaneously with a 12.8
12.8 arcminute eld of view. The observations were done with the newly installed 1600
telescope of the North-West University, South Africa.
In order to do a variability search, periodic stars need to be identi ed from the cluster
data, where a typical data set may contain thousands of scienti c images. In addition
to the main motivation for this study, a pipeline was created in order to automate the
photometry and data reduction processes. A Lomb-Scargle transform was applied to the
stellar light curves in order to identify periodic sources. 354 signi cantly periodic stars
were identi ed from the 3182 observed stars. Amongst them, two new possible Cephei
stars were found together with a possible slowly pulsating B star (SPB), and numerous
eclipsing binary systems.
By using photometry of this region obtained by Forbes & Short (1996), instrumental
magnitudes were transformed to a standard system in order to compare photometry
results. From the constructed colour magnitude diagram of the two clusters, it could be
seen that some stars, indicated by Forbes & Short (1996) to be cluster members, were
in fact eld stars belonging to neither cluster. The reduction and photometry pipeline was implemented successfully on the data set,
which also highlighted the importance of instrumentation and correct data analysis
procedures. Possible improvements were identi ed in order to overcome di culties experienced
during this study. / Thesis (MSc (Space Physics))--North-West University, Potchefstroom Campus, 2013
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258 |
A search for pulsating B-type variable stars in the southern open clusters NGC 6204 and Hogg 22 / Jacobus Johannes (Jaco) MentzMentz, Jacobus Johannes January 2013 (has links)
The theory of stellar evolution and stellar structure relies on the observation of stars
in di erent phases of their evolutionary cycle. The relation between observations and
theory can be strengthened by obtaining observational data of a large sample of stars in a particular evolutionary phase. The search for Cephei stars, as conducted in this study,
can contribute to the sample of known Cephei stars, where these interesting stars are
massive non-supergiant early B-type stars, displaying pulsating behaviour which is not
well understood.
Stars tend to form in clusters where it can therefore be expected that young massive
stars can be found in open clusters. For this reason two young southern open clusters
were observed in order to search for B-type pulsating stars. The region of NGC 6204
and Hogg 22 was observed over a period of thirteen nights in Johnson B, V and I bands.
NGC 6204 is believed to be the oldest cluster of the two at a distance of 0.8 kpc while the
much younger Hogg 22 is more distant at 2.8 kpc. These two open clusters are located
6 arcminutes apart which made it possible to observe them simultaneously with a 12.8
12.8 arcminute eld of view. The observations were done with the newly installed 1600
telescope of the North-West University, South Africa.
In order to do a variability search, periodic stars need to be identi ed from the cluster
data, where a typical data set may contain thousands of scienti c images. In addition
to the main motivation for this study, a pipeline was created in order to automate the
photometry and data reduction processes. A Lomb-Scargle transform was applied to the
stellar light curves in order to identify periodic sources. 354 signi cantly periodic stars
were identi ed from the 3182 observed stars. Amongst them, two new possible Cephei
stars were found together with a possible slowly pulsating B star (SPB), and numerous
eclipsing binary systems.
By using photometry of this region obtained by Forbes & Short (1996), instrumental
magnitudes were transformed to a standard system in order to compare photometry
results. From the constructed colour magnitude diagram of the two clusters, it could be
seen that some stars, indicated by Forbes & Short (1996) to be cluster members, were
in fact eld stars belonging to neither cluster. The reduction and photometry pipeline was implemented successfully on the data set,
which also highlighted the importance of instrumentation and correct data analysis
procedures. Possible improvements were identi ed in order to overcome di culties experienced
during this study. / Thesis (MSc (Space Physics))--North-West University, Potchefstroom Campus, 2013
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Sur les origines photosphériques des structures dans les vents des étoiles chaudes et lumineusesRamiaramanantsoa, Tahina 08 1900 (has links)
No description available.
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Contribuições ao uso de diodos emissores de luz em iluminação públicaRodrigues, Cláudio Roberto Barbosa Simões 17 December 2012 (has links)
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Previous issue date: 2012-12-17 / No intuito de aportar contribuições ao uso de diodos emissores de luz (ou LEDs, do
inglês Light Emmiting Diodes) em sistemas de iluminação pública, cobrindo lacunas
existentes no cenário nacional, este trabalho traz uma ampla análise sobre este tema. São
apresentados conceitos básicos da fotometria clássica e um estudo sobre adaptações da
fotometria para baixos níveis de luminância, que é a condição observada nas vias públicas
durante o período noturno. Propõe-se a utilização de métricas escotópicas em sistemas de
iluminação pública, uma vez que estas melhor representam a real sensação visual (se
comparadas às métricas clássicas – fotópicas) nas condições de iluminamento típicas
observadas nestes sistemas. Aspectos gerais da iluminação pública e um histórico da evolução
do sistema nacional são brevemente apresentados bem como uma discussão sobre a situação
atual deste sistema e das tecnologias utilizadas. O trabalho traz também um estudo sobre
características ópticas, elétricas e mecânicas dos LEDs e uma análise dos diferentes tipos de
LEDs brancos mais utilizados (HB – High Brightness – e HP – High Power – LEDs).
Algumas normas e recomendações aplicáveis à utilização de LEDs em iluminação pública são
analisadas e discutidas, com o intuito de se investigar lacunas ainda não cobertas pela
normatização existente. Análises de resultados de ensaios de laboratório e de campo, inéditos
no país, realizados com alguns modelos de luminárias LED para iluminação pública
disponíveis no mercado, são também apresentadas. Um estudo sobre acionamento de LEDs é
realizado, abordando técnicas de equalização de corrente entre arranjos série de LEDs
associados em paralelo e diferentes tipos de circuitos de acionamento para LEDs. São
propostas, analisadas e implementadas uma estrutura inédita de baixo custo para a equalização
de corrente e um circuito para o acionamento de LEDs baseado na integração de dois
conversores cc cc não isolados. A topologia de dois estágios proposta é composta por um
conversor boost no primeiro estágio, utilizado para a correção do fator de potência e por um
conversor buck no segundo estágio, utilizado para o controle da corrente nos LEDs. Por fim, o
acompanhamento da implantação e do desempenho, ao longo de dez meses, do projeto piloto
de iluminação pública empregando LEDs instalado no anel viário da Faculdade de Engenharia
da UFJF é apresentado. / In order to present contributions to the use of light emitting diodes (LEDs) in public
lighting systems, covering gaps on the national scenario, this work encompasses abroad
analysis related to this issue. Basic concepts of classical photometry are presented and so a
study of photometry’s adaptations for low luminance levels. It is proposed the use of scotopic
metrics for street lighting systems, since they can better represent the actual visual sensation
(when compared to the classical one – photopic metrics) on its typical nighty conditions.
General aspects of street lighting and the history of the national’s public lighting system are
briefly presented as well as a discussion about the current situation of the Brazilian system
and technologies adopted. The work also brings a study of mechanical, electrical and optical
characteristics of LEDs and an analysis of the two different types of commonly used white
LEDs (HB – High Brightness – and HP – High Power - LEDs). Some standards and
recommendations related to the use of LEDs in street lighting are analyzed and criticized,
with the aim of show some gaps not yet covered by the existent standards. An unprecedented
analysis regarding laboratory and field test benchmarking, taken for some luminaires
available in commerce, is also presented. A study of LED driving is presented, covering
equalization techniques for parallel LEDs strings and different types of LED driving circuits.
It was proposed, analyzed and implemented a novel and low cost structure for current
equalization and an LED driver, based on the integration of two non-isolated dc dc converters.
This proposed two stages topology is composed by a boost converter, on the first stage,
employed to the power factor correction and a buck converter, on the second stage, to control
the LED’s current. Finally, the process of monitoring the installation and the performance,
during ten months, of the LEDs public lighting pilot project, on the roadway belt of
Engineering Faculty of UFJF is presented.
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